Gilead Sciences' hepatitis C drug is racking up record-setting sales. Vertex Pharmaceuticals' drug is the first to treat an underlying cause of cystic fibrosis. The newest drug from Pharmacyclics treats rare blood cancers.

All these medicines have something in common - besides the fact that their high prices draw strong criticism from insurers and others.

These therapies all recently won a time-saving approval from the U.S. Food and Drug Administration, thanks in part to a new effort to quicken the development of cutting-edge drugs.

Patient advocacy groups and pharmaceutical companies, which on average spend $1 billion and a decade on every new drug that reaches consumers, often criticize the FDA for slowing access to promising therapies. Starting in July 2012, the agency made its latest attempt to improve by putting some experimental drugs in a special program: a "breakthrough therapy designation."

Sought-after program

Since then, several drugs that earned the label have made headlines for their ability to fight difficult diseases, and the FDA sees the program as a success. But industry observers debate how to measure that success - and whether the policy helps boost drug prices.

"Over the last two years, the pathway has been very, very popular," said Rob Aggarwal, co-founder of Novel Health Strategies, a consulting firm. "Every company, every pharmaceutical firm, basically wants to get this designation if they have something that looks more promising from the average."

To qualify, the company must show evidence suggesting that a drug could be much better at treating serious or life-threatening conditions than existing therapies. Companies then receive more intensive FDA guidance as drugs are tested, helping cut through bureaucratic red tape.

The FDA has received more than 200 requests for a drug to qualify and has granted 56. Seven have won approval for market, including Sovaldi, the hepatitis C pill by Gilead in Foster City, which costs $84,000 for 12 weeks' worth.

Vertex's cystic fibrosis drug, priced at $311,000 a year, was a "breakthrough." So was Imbruvica, which treats rare blood cancers. Made by Pharmacyclics in Sunnyvale and Johnson & Johnson, it costs $98,000 to $130,800 a year.

So far, these drugs share the dubious honor of giving rise to a debate over drug costs. Sovaldi's cost is the target of a U.S. Senate investigation. Cystic fibrosis patients are suing in Arkansas, alleging that the state's Medicaid program is denying them Vertex's drug because of its cost. And some doctors question Imbruvica's price; in an editorial last year, a group of physicians said blood cancer therapies that cost $100,000 annually were "unsustainable."

Any mechanism that lets a drug reach the market first gives companies a head start on treating patients - and perhaps setting prices.

"Breakthrough therapies are likely to be specialty drugs that come at a high cost, and there is no guarantee that health insurers will cover a substantial portion of those costs," analysts recently wrote in Health Affairs. "It is possible that a manufacturer's pricing strategy will be driven in part by its ability to market a drug based on its status as a breakthrough therapy."

Why prices are high

But RBC Capital Markets analyst Michael Yee said the label isn't directly responsible for the price, which accounts for other factors, such as the drug's quality and safety and the cost of research and development.

"You have a drug that is significantly better than existing drugs or it's the first drug for that indication," he said. "It's justifying a premium price because of the unmet need."

In some cases, the label does seem to significantly shave time off the approval process. Gazyva, a drug for chronic lymphocytic leukemia by Genentech in South San Francisco, went from the first clinical trial to approval in six years - extremely fast in the pharmaceutical world.

The designation is also positive publicity for companies, which send out press releases and alert investors. The FDA is pleased with the program too: An agency executive called it a "virtual overnight success" in a May blog post.

But industry analysts disagree about how useful the label is. It's tough for an outsider to distinguish it from the FDA's other, similar-sounding programs - "fast track," "accelerated approval" and "priority review" - even though they work in slightly different ways to speed up drug development for diseases.

And it's questionable whether all "breakthrough" drugs have truly benefited from the label. Gilead's Sovaldi got the designation at the very end of its development in October and was approved a mere two months later.

The program will likely become more useful over time as new drugs make their way into the pipeline, said Jeff Allen, executive director of Friends of Cancer Research. The think tank and advocacy group pushed for the program to become law.

"It's meant to expedite highly promising drugs showing a substantial effect very early on," he said.

Overly hasty?

Then there's the safety question. A sped-up process presents the risk that a drug can go to market before its benefits or side effects are fully understood.

The label can confuse patients "when they see 'breakthrough' for drugs that are not curative and don't extend life by more than three to four months," said Aggarwal, who analyzed the program in an April paper in the journal Nature Biotechnology.

While the process may be imperfect, Yee said, the intent behind it benefits companies and patients alike.

"If a drug is clearly efficacious with minimum side effects, and it sounds like a breakthrough therapy," he said, "why do we need to spend time debating it while people are dying?"